Check for updates for a user script only if it has an update URL.

chrome/browser/extensions/extension_updater.cc

Index: chrome/browser/extensions/extension_updater.cc
diff --git a/chrome/browser/extensions/extension_updater.cc b/chrome/browser/extensions/extension_updater.cc
index 232d9ddd56123e84eaeed776511a650a27217996..31392cc65658fba6da7847de4ca8c1fcd654fc42 100644
--- a/chrome/browser/extensions/extension_updater.cc
+++ b/chrome/browser/extensions/extension_updater.cc
@@ -159,6 +159,13 @@ ManifestFetchesBuilder::ManifestFetchesBuilder(
 }
 
 void ManifestFetchesBuilder::AddExtension(const Extension& extension) {
+  // Skip extensions with empty update URLs converted from user
+  // scripts.
+  if (extension.converted_from_user_script() &&
+      extension.update_url().is_empty()) {
+    return;
+  }
+
   AddExtensionData(extension.location(),
                    extension.id(),
                    *extension.version(),